The present invention relates generally to printed materials and more particularly to trimming units for trimming edges of a book.
U.S. application No. 2002/0034428 discloses a trimmer for trimming excess margins along one, two or three edges of a perfect bound book. The book is gripped by a book holder, and a shearing blade cuts the edges of the book. The shearing blade has a flat edge and reciprocates.
European Patent Application No. 1 201 379 discloses a three-sided trimmer having a top edge cutting knife, a bottom edge cutting knife and a fore edge cutting knife, all with flat edges and reciprocating.
European Patent Application No. 0 893 277 discloses a trimmer, particularly for trimming book backs. A milling cutter has a disc-shaped body specially shaped teeth. The trimmer is a rotary cutter.
A problem associated with prior art trimmers used for trimming books is the delamination of the cover of a book from the interior sheet material, or the tearing of the book material. This trim defect is typically called “chipout” or “tearout”.
It has been known to score the spine of the book with scoring knives before the head and foot of the book are trimmed.